There has been increasing debate in the medical and health services research literature about the contribution of medical technologies to the rising costs of hospital care. There are few data, however, that document how the use of hospital technologies has changed over time. Moreover, few previous studies of medical technology use have controlled well for the severity of illness of the patients studied, thus leaving open to question whether their findings were more the result of actual changes in the ways technologies are used or changes in the severity of illness studied. This study will test the null hypothesis that, after standardizing for severity of illness, there was no change in the use of medical technologies for patients hospitalized at the University of California, San Francisco in the years 1972, 1977 and 1982. Ten diagnoses will be studied: acute asthma, acute myocardial infarction, lung cancer, respiratory distress syndrome of the newborn, cataract excision, cesarean section and vaginal delivery, kidney transplant, stapedectomy and total hip replacement. Data will be collected from both billing and medical records. Analytic methods will include comparison of service use and charges between years by chi square, t-tests and analyses of variance and covariance. In addition to the proposers' previous work in this area, this study will provide information that will allow a more enligthened debate about the reasons for the rising costs of hospital care and the contribution of hospital technologies to this rise.